This invention relates generally to fasteners and more specifically to a double ended fastening system.
It is common to arc weld an enlarged circular end of a threaded metal stud onto a sheet metal body panel of an automotive vehicle. Various parts are then inserted upon the single threaded stud and an internally threaded nut is rotationally inserted onto the stud. However, the nut installation is a time consuming process which often leads to undesirably varying fastening forces.
It is also known to use a pneumatic tool to swage and compress an unthreaded metal nut or sleeve over the arc welded stud in a torque-free manner. This torque-free construction employs a two-part stud, separated by a reduced diameter neck. The tool pulls off the threaded end after the nut is secured to the remaining threaded part of the stud. The nut can be unscrewed and reused. This stud is almost exclusively used without the need for holes in the sheet metal body panel. However, it is often undesirable to arc weld a stud directly to the sheet metal body panel. For example, the welding station is fairly expensive and takes up considerable space in the assembly plant. Furthermore, it is impractical to arc weld such a conventional stud to a plastic component instead of to the body panel. Thus, there is a need to secure a stud fastener directly to a plastic component while using a torque-free nut and a two segment threaded stud, in order to secure a plastic component to a body panel.
It is also known to press insert, insert mold or ultrasonically insert a knurled fastener into a plastic panel. See, for example, U.K. Patent Application GB 2 274 697 A entitled xe2x80x9cPart Mounting Device and Methodxe2x80x9d which was published on Aug. 3, 1994. However, the bolt shown in FIG. 7B of the U.K. application is of a conventionally threaded variety using a standard threaded nut.
In accordance with the present invention, the preferred embodiment of a double ended fastening system includes a first segment for engaging a component and a second threaded segment for engaging a nut. In another aspect of the present invention, the first segment is threaded and a lateral projection or flange is present. A further aspect of the present invention provides a third segment, joined to the second segment by a reduced diameter neck, which is removable from the second segment after the nut is compressibly secured to the second segment of the stud. Still another aspect of the present invention employs a component having a stud receiving portion made of a polymer or soft metal. In yet a further aspect of the present invention, a self-drilling and self-tapping feature is provided on the first segment of the stud.
The present invention is advantageous over traditional devices, in that the present invention fastener is secured to the component off of the quickly moving assembly line and then the component and fastener assembly are quickly attached to the body panel with a compression sleeve or nut. Engagement of the nut onto the threaded stud does not require any torque upon the nut or stud, thereby maintaining the desired mounting of the stud to the component. Furthermore, a low cost nut can be used since it does not employ internal threads prior to insertion upon the stud. Moreover, the nut can be unscrewed and reused. The component-to-panel fastening also advantageously occurs on a single side of the body panel and is very quickly installed, compared to pre-threaded nuts, since the traditional nut run-down time is not required. Thus, the no torque fastening system of the present invention is ideally suited for direct mounting to polymeric and soft metal components. Additional advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.